The invention relates to a loudspeaker with a front-mounted sealing element which abuts a wall and acoustically seals against the wall when the loudspeaker is installed, and to a method of manufacturing a loudspeaker of this type.
As shown schematically in FIGS. 1 and 2, loudspeakers are typically sealed against the interior door panels of automobiles with open-cell foam sealing strips which may or may not be impregnated and have cross-sectional dimensions of 2xc3x974 mm to 20xc3x9725 mm. The foam sealing strip 12 can be attached to the loudspeaker frame, to a loudspeaker frame adapter, a loudspeaker support or a loudspeaker grille using an adhesive. The foam sealing strip 12 shown in FIG. 1 has an annular shape with a square cross-section and is affixed to the annular outer region of the loudspeaker cover grille 10 with an adhesive. The end face of the foam sealing strip 12 facing away from the loudspeaker cover grille 10 makes contact with the interior door panel 18 over a surface area to provide an acoustic seal. In addition, the door panel 18 has openings 19 which allow the acoustic waves produced by the loudspeaker to enter the vehicle compartment. The loudspeaker itself can be attached to the interior wall 16 of the door using bores 11,17 provided in the loudspeaker and in the inner wall 16 of the door, respectively.
Foam sealing strips disadvantageously do not produce an absolute seal due to their open cell construction. Moreover, adhesion of the foam sealing strips is. strongly dependent on the environmental conditions. Car buyers have been known to complain about non-adhering, poorly adhering or completely detached foam strips, when such seals are employed between the loudspeakers and the interior door panel. It has also been observed that such problems occur more frequently when the automobile and hence also the loudspeakers with the attached foam sealing strips are subjected to large changes in ambient temperature and/or to high humidity.
The problem becomes more pronounced with loudspeakers having a relatively small diameter of, for example, between approximately 130 and 160 mm, because the foam sealing strips have a smaller radius as compared to larger loudspeakers, thereby producing even greater separation forces under changing ambient temperature and/or high humidity conditions.
Foam sealing strips attached with an adhesive may disadvantageously also preclude prefabrication and/or complete assembly of the loudspeaker at a factory. Conventional foam sealing strips may also impede and even prevent online manufacture of the loudspeaker on an automatic loudspeaker assembly is line at reasonable cost.
It is therefore an object of the present invention to provide a loudspeaker which can provide an optimal acoustic seal, is easy to manufacture, and has a good temperature and humidity resistance. It is another object to provide a method for its manufacture.
According to an aspect of the invention, the loudspeaker includes a sealing element made of a thermo-elastic polymer which is molded as a single piece to the front side of the loudspeaker.
The sealing element can be molded to a frame supporting the loudspeaker, to a loudspeaker adapter, or to a loudspeaker cover grille or to a similar component of the loudspeaker using a two-component technique. Advantageously, the sealing element is made of a thermoplastic elastomer (TPE), wherein the cross-section of the TPE sealing element is designed to have an elastic deformation range capable of bridging a gap located between the loudspeaker and a wall to which the loudspeaker is to be mounted. The cross-section, for example, can be Z-shaped or approximately Z-shaped. The TPE sealing element may also be made of a polypropylene material, such as poly (carbodiimide) polymer and/or DAPLEN(trademark).
The TPE sealing element may be molded directly to the loudspeaker frame, the loudspeaker frame adapter or the loudspeaker cover grille. Advantageously, the TPE sealing element has a substantially annular shape, when viewed from the top of the loudspeaker, i.e., normal to the front side of the loudspeaker.
The loudspeaker frame may be made of plastic, and the TPE sealing element can be molded to a front end wall of the loudspeaker frame or the loudspeaker frame adapter. In addition, the front end wall of the loudspeaker frame or of the loudspeaker frame adapter may include an annular groove, with a wall section of the TPE sealing element molded into the groove. The TPE sealing element may also include a projecting sealing lip facing the wall against which the loudspeaker is to be sealed. A loudspeaker of this type is particularly suited for installation in an automobile door, wherein the loudspeaker can be attached to an interior wall portion of the door, with the TPE sealing element sealing against the interior door panel.
The loudspeaker according to the invention has a the following advantages:
providing a hermetic seal, since the material of the sealing element is impermeable to air,
eliminating adhesion problems between the sealing element and the loudspeaker, because the sealing element is molded to the loudspeaker and is therefore connected to the loudspeaker to form a single piece,
enabling online manufacturing.